Sorry Michel I was following your guidelines to upload the error message but getting and error as "You cannot use links until you have posted more than 5 messages". So prepare a text file as an attachment.

Almost all SYS packages are invalid including XML functions!
First, as SYS, reexecute (in Windows notation):
%ORACLE_HOME%\rdbms\admin\catalog.sql
%ORACLE_HOME%\rdbms\admin\catproc.sql
then come back with the following:

select owner, object_type, count(*) from dba_objects
where status != 'VALID' and owner like '%SYS%' order by 1, 2;